Friday, April 23, 2010

New research reveals a brain circuit that seems to underlie the ability of humans to resist instant gratification and delay reward for months, or even years, in order to earn a better payoff. The study, published by Cell Press in the April 15 issue of the journal Neuron, provides insight into the capacity for "mental time travel," also known as episodic future thought, that enables humans to make choices with high long-term benefits.

"Humans normally prefer larger over smaller rewards, but this situation can change when the larger rewards are associated with delays," explains lead study author, Dr. Jan Peters from the Department of Systems Neuroscience at the University Medical Center Hamburg-Eppendorf in Germany. "Although there is no doubt that humans discount the value of rewards over time, in general, individuals exhibit a particularly significant ability to delay gratification."

Several models have been proposed to explain the neural basis of assigning relative value to multiple rewards at different points in time (also known as "intertemporal decision making") in humans. However, many questions remain unanswered, and the brain regions and mechanisms involved in this process are unclear. Dr. Peters, and coauthor Professor Christian Büchel, used functional magnetic resonance imaging (fMRI), neural coupling analyses, and extensive behavioral paradigms to examine the interactions between episodic future thought and intertemporal decision making.

Human subjects had to make a series of choices between smaller immediate and larger delayed rewards while brain activity was measured with fMRI. Importantly, in addition to this standard control condition, the participants were presented with "cues" that referred to real subject-specific future events planned for the respective day of reward delivery. The researchers observed that the more the cues induced spontaneous episodic imagery, the more subjects changed their preferences toward patient, future-minded choice behavior.

Further, the neuroimaging data revealed that signals in the anterior cingulate cortex (ACC), a part of the brain implicated in reward-based decision making, and functional coupling of this region with the hippocampus, linked with imagining the future, predicted the degree to which forward thinking modulated individual preference functions.

"Taken together, our results reveal that vividly imagining the future reduced impulsive choice," concludes Dr. Peters. "Our data suggest that the ACC, based on episodic predictions involving the hippocampus, supports the dynamic adjustment of preference functions that enable us to make choices that maximize future payoffs."

A team of investigators from Columbia, Rockefeller and Stanford Universities has identified a new gene involved in hair growth, as reported in a paper in the April 15 issue of Nature. This discovery may affect future research and treatments for male pattern baldness and other forms of hair loss.

The researchers found that the gene, called APCDD1, which causes a progressive form of hair loss beginning in childhood (known as hereditary hypotrichosis simplex). The disease is caused by a phenomenon called hair follicle miniaturization – the same key feature of male pattern baldness. When hair follicles go through this miniaturization process, they shrink or narrow, causing the thick hair on the head to be replaced by thin, fine hair, known as "peach fuzz."

"The identification of this gene underlying hereditary hypotrichosis simplex has afforded us an opportunity to gain insight into the process of hair follicle miniaturization, which is most commonly observed in male pattern hair loss or androgenetic alopecia," said Angela M. Christiano, Ph.D., professor of dermatology and genetics & development at Columbia University Medical Center, and lead author of the study. "It is important to note that while these two conditions share the same physiologic process, the gene we discovered for hereditary hypotrichosis does not explain the complex process of male pattern baldness."

The team made their discovery by analyzing genetic data from a few families from Pakistan and Italy with hereditary hypotrichosis simplex. They found a common mutation in the APCDD1 gene, which is located in a specific region on chromosome 18 that has been shown in previous studies to be implicated in other forms of hair loss, including androgenetic alopecia and alopecia areata, hinting at a broader role in hair follicle biology.

Importantly, the researchers found that APCDD1 inhibits a signaling pathway that has long been shown to control hair growth in mouse models, but has not been extensively linked to human hair growth. Laboratory researchers have targeted this pathway, known as the Wnt signaling pathway, to turn on or off hair growth in mice, but, until now, the pathway did not appear to be involved in human hair loss. This finding is significant because it provides evidence that hair growth patterns in humans and in mice are more similar than previously believed.

"We have at last made a connection between Wnt signaling and human hair disease that is highly significant," said Dr. Christiano. "We have years of beautiful data in our field about hair growth in mice, but this is the first inroad into showing that the same pathway is critical in human hair growth. This is the first mutation in a Wnt inhibitor that deregulates the pathway in a human hair disease."

"Furthermore, these findings suggest that manipulating the Wnt pathway may have an effect on hair follicle growth – for the first time, in humans," said Dr. Christiano. "And unlike commonly available treatments for hair loss that involve blocking hormonal pathways, treatments involving the Wnt pathway would be non-hormonal, which may enable many more people suffering from hair loss to receive such therapies."

Dr. Christiano and her team are now working to understand the complex genetic causes of other forms of hair loss including alopecia areata, with the hope of eventually developing new, effective treatments for these conditions.

Researchers have devised a new kind of random number generator, for encrypted communications and other uses, that is cryptographically secure, inherently private and – most importantly – certified random by laws of physics.

That is important because randomness is surprisingly rare. Although the welter of events that transpire in the course of daily life can certainly seem haphazard and arbitrary, none of them is genuinely random in the sense that they could not be predicted given sufficient knowledge. Indeed, true randomness is almost impossible to come by.

That situation is a source of urgent and persistent concern to cryptographers who need to encrypt valuable data and messages by using a long string of random numbers to form a "key" to encode and decode the information. For practical purposes, encoders typically employ various mathematical algorithms called "pseudo-random number generators" to approximate the ideal. But they can never be completely certain that the system used to produce those number strings is invulnerable to adversaries or that a seemingly random sequence is not, in fact, predictable in some manner.

Now, however, a team of experimentalists from the Joint Quantum Institute (JQI), in partnership with European quantum information scientists, has demonstrated a method of producing a certifiably random string of numbers based on fundamental principles of quantum mechanics. They report their results in the 15 April 2010 issue of Nature.

"Classical physics simply does not permit genuine randomness in the strict sense," says JQI Fellow Chris Monroe, who led the experimental team. "That is, the outcome of any classical physical process can ultimately be determined with enough information about initial conditions. Only quantum processes can be truly random – and even then, we must trust that the device is indeed quantum and has no remnant of classical physics in it."

In quantum mechanics, the science of matter and energy on the smallest scales, specific properties of objects (such as the position of an electron or the polarization of a photon) can be inherently uncertain. Although the probability of any particular property can be calculated in advance, those properties take on particular values only when measured; and the values are intrinsically random. So in theory, one could obtain a series of random numbers by performing a series of quantum measurements that were entirely independent of one another.

"Such a sequence would, of course, be intrinsically random," says Dzmitry Matsukevich of JQI, a coauthor of the report in Nature. "However, most people would probably prefer to buy an existing quantum device rather than build a quantum random number generator themselves. Unfortunately in this case it is very difficult to ensure that the device produces a string of random numbers that is not known to anyone else. For example, instead of a real quantum random number generator, someone might sell you a "black box" device that has a memory filled with random numbers loaded in advance. This device would probably pass all existing tests of randomness. But someone would still have a copy of all the numbers."

There is, however, a procedure that guarantees the presence of truly random quantum measurements, generated only at – and completely unique to – a particular place and time, which might be termed "private randomness." It was invented by physicist John Bell in 1964 to test a central hypothesis of quantum mechanics: namely, that two objects such as photons or matter particles can enter an exotic condition called "entanglement" in which their states become so utterly interdependent that if a measurement is performed to determine a property of one (which will, of course, be a random value), the corresponding property of the other is instantly determined as well, even if the two objects are separated by distances so large that no information could possibly pass between them after the measurement is made on the first object.

Many scientists, notably including Albert Einstein, found that notion completely unacceptable, arguing instead that so-called "entangled" objects must actually possess some hidden variables which give the objects specific properties in advance of a measurement. Otherwise, a purely local measurement of Object 1 would have an instantaneous effect on Object 2, even if Object 2 was light-years away at the time of the measurement – a phenomenon Einstein dismissed as "spooky action at a distance." For 30 years, there was no convincing way of determining experimentally whether Einstein was right or wrong.

Then Bell came up with a revolutionary method that involved counting the correlations between measurements made on the two objects as the measuring devices were switched among numerous different orientations. Bell showed mathematically that if the objects were not entangled, their correlations would have to be smaller than a certain value, expressed as an "inequality." If they were entangled, however, the correlation rate could be higher, "violating" the inequality. Various kinds of Bell tests performed in recent decades on entangled systems have shown such inequality violation, and thus confirmed the nonlocality of quantum mechanics. But the JQI experiment was the first to violate a Bell inequality between systems separated over a distance without missing any of the events.

"Violation of a Bell inequality is possible only if the system obeys the laws of quantum mechanics," Matsukevich says. "Therefore if we verify a Bell inequality violation between isolated systems while not missing events, we can ensure that our device produces private randomness. We don't need the atoms to be too far apart, only far enough so that they could be shielded from each other, as would be done anyway in a real cryptographic setting."

To do so, the JQI group placed a single atom in each of two completely isolated enclosures spaced a meter apart. They then proceeded to entangle the two atoms using a now-familiar method based on single photons travelling between the atoms.

Every time their apparatus signaled that entanglement had been achieved, the researchers rotated each atom on its axes according to a random schedule and then took a measurement of each atom's emitted light. The value from each of two atoms was then used to generate a binary number.

The researchers performed more than 3000 consecutive entanglement events in the course of about a month, confirming Bell inequality violation and in the process generating a string of 42 random private binary digits at a 99% confidence level. As a result, they write in Nature, "we can, for the first time, certify that new randomness is produced in an experiment without a detailed model of the device." That is, the process relies only on achieving entanglement and performing operations on the entangled objects, not on the specific details of how entanglement was achieved.

At present, "the random bit generation rate is extremely slow," said Monroe, "but we expect speedups by orders of magnitude in coming years as we more efficiently entangle the atoms, perhaps by using atom-like quantum systems embedded in a solid-state chip." Then by violating the Bell inequality over much larger distances, Monroe added that "such a system could be deployed for a more secure type of data encryption."

Highly dangerous Cryptococcus fungi love sugar and will consume it anywhere because it helps them reproduce. In particular, they thrive on a sugar called inositol which is abundant in the human brain and spinal cord.

To borrow inositol from a person’s brain, the fungi have an expanded set of genes that encode for sugar transporter molecules. While a typical fungus has just two such genes, Cryptococcus have almost a dozen, according to Joseph Heitman, MD, PhD, chairman of the Duke Department of Molecular Genetics and Microbiology.

“Inositol is abundant in the human brain and in the fluid that bathes it (cerebral spinal fluid), which may be why this fungus has a predilection to infect the brain and cause meningitis,” Heitman said. “It has the machinery to efficiently move sugar molecules inside of its cells and thrive.”

This specialized brain attack likely occurred because these fungi adapted to grow on plants in the wild, which also are abundant in inositol, said lead author Chaoyang Xue, PhD, formerly a postdoctoral research associate in the Heitman lab and now an assistant professor at the Public Health Research Institute at the University of Medicine and Dentistry of New Jersey. “In fact, this pathogenic yeast has more inositol transporters than all other fungi we have compared it to in the fungal kingdom, based on what we know from genome research.”

The team of researchers discovered that inositol stimulates Cryptococcus to sexually reproduce. “A connection between the high concentration of free inositol and fungal infection in the human brain is suggested by our studies,” Xue said. “Establishing such a connection could open up a new way to control this deadly fungus.”

Cryptococcus’ love for sugar may also be a fungal Achilles' heel, Heitman said. “Now scientists may be able to target the fungi by developing ways to put them on the fungal equivalent of an Atkin's low-carbohydrate diet so they will stop multiplying.”

He said researchers could use the new findings to devise different types of strategies to block Cryptococcus infections.

These studies will be reported in the inaugural issue of the journal mBio, which will be launched in May by the American Society for Microbiology as an online journal that spans all areas of microbiology.

The older we get, the more different we become. This is the conclusion of a study that followed people from their 70th to their 90th year of life.

Old people are usually thought of as a rather homogenous group – they are considered to be ill, lonely and unable to take care of themselves. But the truth is that the differences among people grow with age,' says Bo G Eriksson, University of Gothenburg.

As part of his doctoral thesis, Eriksson studied participants of the extensive and unique so-called H-70 study, which is based on a group of randomly selected individuals born in 1901 and 1902 who were followed closely over their entire lifetimes. Eriksson's study focuses on the period from their 70th to their 90th year of life. It turns out that people become more and more different as they age.

'The perception of old people having similar interests, values and lifestyles can lead to age discrimination. However, I found that, as people age, these stereotypes become more and more untrue,' says Eriksson.

Eriksson also studied differences in causes of death with increasing age, and again found indications of possible age discrimination.

Eriksson explored how social conditions can affect longevity, and found four mechanisms at work. The first two relate to creation of social facts. Examples of social facts include promises and agreements that strengthen the identities of individuals. The third mechanism relates to how a person builds and maintains self esteem by successfully responding to challenges. The fourth mechanism consists of everyday conversations, which decrease anxiety and offer support in everyday decision making, improves attention and gives the brain and the memory a healthy workout.

'Taken together, these mechanisms also contribute to increased everyday activity, which has some beneficial physical effects,' says Eriksson.

Moreover, Eriksson applied two different methods to predict people's lifespan: one that researchers commonly use when calculating probability and one that is based on artificial neural networks (ANN), which is common in research on artificial intelligence. It turned out that the ANN method was more effective in complex situations where traditional methods do not work. ANN may therefore be appropriate in evaluations of results produced with traditional research methods.

Light-emitting diodes, which employ semiconductors to produce artificial light, could reduce electricity consumption and lighten the impact of greenhouse gas emissions. However, moving this technology beyond traffic signals and laser pointers to illumination for office buildings and homes—the single largest use of electricity—requires materials that emit bright, white light cheaply and efficiently. White light is the mix of all the colors, or wavelengths, in the visible spectrum.

Organic light-emitting diodes (OLEDs), based on organic and/or polymer semiconductor materials, are promising candidates for general lighting applications, as they can cover large-area displays or panels using low-cost processing techniques. Indeed, single-color OLED displays are already available commercially. A mix of red-, green- and blue-emitting materials can be used to generate white light, but these bands of color often interact with one another, degrading device performance and reducing color quality.

Using polymer nanoparticles to house light-emitting ‘inks’, scientists at the Molecular Foundry, a U.S. Department of Energy nanoscience center located at Berkeley Lab, and the University of California, Berkeley, have made a thin film OLED using iridium-based guest molecules to emit various colors of visible light. The polymer nanoparticle surrounding a guest light-emitter serves as a ‘do not disturb’ sign, isolating guest molecules from one another. Each guest can then emit light without pesky interactions with neighboring nanoparticles, resulting in white luminescence.

“This simple and bright approach to achieving nanoscale site isolation of phosphors opens a new door for facile processing of white OLEDs for solid state lighting,” said Biwu Ma, a staff scientist with the Molecular Foundry’s Organic Nanostructures Facility who contributed to this study. With this proof-of-concept device under their belts, Ma and his colleagues plan to vary the ratio of each color nanoparticle in the OLED to enhance efficiency and brightness. White light from OLEDs can be adjusted from cooler to warmer whites, making these materials easy to use in office or home environments. Buildings account for more than 40 percent of carbon emissions in the United States, so replacing even a fraction of conventional lighting with OLEDs could result in a significant reduction in electricity use.

Allergies have become a widespread in developed countries: hay fever, eczema, hives and asthma are all increasingly prevalent. The reason? Excessive cleanliness is to blame according to Dr. Guy Delespesse, a professor at the Université de Montréal Faculty of Medicine.

Allergies can be caused by family history, air pollution, processed foods, stress, tobacco use, etc. Yet our limited exposure to bacteria concerns Dr. Delespesse, who is also director of the Laboratory for Allergy Research at the Centre hospitalier de l'Université de Montréal.

"There is an inverse relationship between the level of hygiene and the incidence of allergies and autoimmune diseases," says Dr. Delespesse. "The more sterile the environment a child lives in, the higher the risk he or she will develop allergies or an immune problem in their lifetime."

In 1980, 10 percent of the Western population suffered from allergies. Today, it is 30 percent. In 2010, one out of 10 children is said to be asthmatic and the mortality rate resulting from this affliction increased 28 percent between 1980 and 1994.

"It's not just the prevalence but the gravity of the cases," says Dr. Delespesse. "Regions in which the sanitary conditions have remained stable have also maintained a constant level of allergies and inflammatory diseases."

"Allergies and other autoimmune diseases such as Type 1 diabetes and multiple sclerosis are the result of our immune system turning against us," says Dr. Delespesse.

Why does this happen? "The bacteria in our digestive system are essential to digestion and also serve to educate our immune system. They teach it how to react to strange substances. This remains a key in the development of a child's immune system."

Although hygiene does reduce our exposure to harmful bacteria it also limits our exposure to beneficial microorganisms. As a result, the bacterial flora of our digestive system isn't as rich and diversified as it used to be.

Dr. Delespesse recommends probiotics to enrich our intestinal flora. Probiotics are intestinal bacteria that have a beneficial impact on health. They've been used for decades to make yogurt. Probiotics have a proven effect on treating diarrhea, and studies are increasingly concluding similar benefits for the immune system and allergies.

Jealousy really is "blinding," according to a new study by two University of Delaware psychology professors. They found that women who were made to feel jealous were so distracted by unpleasant emotional images they became unable to spot targets they were trying to find.

The researchers suggest that their results reveal something profound about social relationships and perception: It has long been known that the emotions involved in social relationships affect mental and physical health, but now it appears that social emotions can literally affect what we see.

The research appears in the April issue of the journal "Emotion," published by the American Psychological Association. UD psychology professors Steven Most and Jean-Philippe Laurenceau and their colleagues tested heterosexual romantic couples in a lab experiment. The romantic partners sat near each other at separate computers. The woman was asked to detect targets (pictures of landscapes) amid rapid streams of images, while trying to ignore occasional emotionally unpleasant (gruesome or graphic) images.

The man was asked to rate the attractiveness of landscapes that appeared on his screen. Partway through the experiment, the experimenter announced the male partner would now rate the attractiveness of other single women.

At the end, the females were asked how uneasy they felt about their partner rating other women's attractiveness.

The finding? The more jealous the women felt, the more they were so distracted by unpleasant images that they could not see the targets. This relationship between jealousy and "emotion-induced blindness" emerged only during the time that the male partner was rating other women, helping rule out baseline differences in performance among the women.

The researchers don't yet know what will happen when the roles are reversed; in these experiments, it was always the women who searched for a target. Future research might reveal whether men tend to be less or more blinded by jealousy.

A British scientific expedition has discovered the world's deepest undersea volcanic vents, known as 'black smokers', 3.1 miles (5000 metres) deep in the Cayman Trough in the Caribbean. Using a deep-diving vehicle remotely controlled from the Royal Research Ship James Cook, the scientists found slender spires made of copper and iron ores on the seafloor, erupting water hot enough to melt lead, nearly half a mile deeper than anyone has seen before.

Deep-sea vents are undersea springs where superheated water erupts from the ocean floor. They were first seen in the Pacific three decades ago, but most are found between one and two miles deep. Scientists are fascinated by deep-sea vents because the scalding water that gushes from them nourishes lush colonies of deep-sea creatures, which has forced scientists to rewrite the rules of biology. Studying the life-forms that thrive in such unlikely havens is providing insights into patterns of marine life around the world, the possibility of life on other planets, and even how life on Earth began.

The expedition to the Cayman Trough is being run by Drs Doug Connelly, Jon Copley, Bramley Murton, Kate Stansfield and Professor Paul Tyler, all from Southampton, UK. They used a robot submarine called Autosub6000, developed by engineers at the National Oceanography Centre (NOC) in Southampton, to survey the seafloor of the Cayman Trough in unprecedented detail. The team then launched another deep-sea vehicle called HyBIS, developed by team member Murton and Berkshire-based engineering company Hydro-Lek Ltd, to film the world's deepest vents for the first time.

"Seeing the world's deepest black-smoker vents looming out of the darkness was awe-inspiring," says Copley, a marine biologist at the University of Southampton's School of Ocean and Earth Science (SOES) based at the NOC and leader of the overall research programme. "Superheated water was gushing out of their two-storey high mineral spires, more than three miles deep beneath the waves". He added: "We are proud to show what British underwater technology can achieve in exploring this frontier - the UK subsea technology sector is worth £4 billion per year and employs 40 000 people, which puts it on a par with our space industry."

The Cayman Trough is the world's deepest undersea volcanic rift, running across the seafloor of the Caribbean. The pressure three miles deep at the bottom of the Trough - 500 times normal atmospheric pressure - is equivalent to the weight of a large family car pushing down on every square inch of the creatures that live there, and on the undersea vehicles that the scientists used to reveal this extreme environment. The researchers will now compare the marine life in the abyss of the Cayman Trough with that known from other deep-sea vents, to understand the web of life throughout the deep ocean. The team will also study the chemistry of the hot water gushing from the vents, and the geology of the undersea volcanoes where these vents are found, to understand the fundamental geological and geochemical processes that shape our world.

"We hope our discovery will yield new insights into biogeochemically important elements in one of the most extreme naturally occurring environments on our planet," says geochemist Doug Connelly of the NOC, who is the Principal Scientist of the expedition. "It was like wandering across the surface of another world," says geologist Bramley Murton of the NOC, who piloted the HyBIS underwater vehicle around the world's deepest volcanic vents for the first time. "The rainbow hues of the mineral spires and the fluorescent blues of the microbial mats covering them were like nothing I had ever seen before."

"Our multidisciplinary approach - which brings together physics, chemistry, geology and biology with state-of-the-art underwater technology - has allowed us to find deep-sea vents more quickly than ever before," adds oceanographer Kate Stansfield of the NOC.

The team aboard the ship includes students from the UK, Ireland, Germany and Trinidad. "This expedition has been a superb opportunity to train the next generation of marine scientists at the cutting edge of deep-sea research," says marine biologist Paul Tyler of SOES, who heads the international Census of Marine Life Chemosynthetic Ecosystems (ChEss) programme.

The expedition will continue to explore the depths of the Cayman Trough until 20th April. The team are posting daily updates on their expedition website at http://www.thesearethevoyages.net/, including photos and videos from their research ship. "We look forward to sharing the excitement of exploring the deep ocean with people around the world," says Copley.

In addition to the scientists from Southampton, the team aboard the ship includes researchers from the University of Durham in the UK, the University of North Carolina Wilmington and the University of Texas in the US, and the University of Bergen in Norway. The expedition members are also working with colleagues ashore at Woods Hole Oceanographic Institution and Duke University in the US to analyse the deep-sea vents.

The expedition is part of a research project funded by the UK Natural Environment Research Council to study the world's deepest undersea volcanoes. The research team will return to the Cayman Trough for a second expedition using the UK's deep-diving remotely-operated vehicle Isis, once a research ship is scheduled for the next phase of their project.